题解 | #汽水瓶#

/*
 * 题目分析: 3空瓶 -> 1瓶, 特殊: 最后2空瓶 -> 1瓶
 * 解题思路: 递归
 */
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        for (int total = sc.nextInt(); total != 0; total = sc.nextInt()) {
            int res = 0;
            while (total >= 3) {
                int tmp_res = total / 3;
                res += tmp_res;
                total = tmp_res + (total % 3);
            }
            if (total == 2) {
                res++;
            }
            System.out.println(res);
        }
    }
}